The present invention relates to telecommunications systems, and more particularly, to telephony interface systems and techniques.
With integration of digital logic circuits into analog circuits operating with DC and AC voltages and currents, a circuit with a BORSCHT function is typically used to interface between analog and digital circuits. BORSCHT stands for the functions of battery feed, over-voltage protection, ringing, signaling, coding, hybrid and testing. The BORSCHT functions are typically contained in a circuit called a subscriber line interface circuit (SLIC). SLIC""s are typically used to interface between a central office and subscriber telephone instruments in a subscriber line interface, which is also called a local loop.
In one aspect of the present invention, a telephony line interface circuit includes a SLIC having an operational amplifier with a composite MOSFET-bipolar driver stage.
In another aspect of the present invention, a method of interfacing a telephony device to a communication medium includes outputting signals to a telephony line with a composite MOSFET-bipolar driver stage.
In yet another aspect of the present invention, a telephony line interface circuit includes a SLIC having a tip amplifier to drive a tip signal of a telephony line, and a ring amplifier to drive a ring signal of the telephony line, each of the tip and ring amplifiers comprising a composite MOSFET-bipolar driver stage.
In yet a further aspect of the present invention, a telephony line interface circuit includes a SLIC having an operational amplifier with a composite MOSFET-bipolar driver stage, and a CODEC coupled to the SLIC.
In yet another aspect of the present invention, a method of interfacing a telephony line to a communications medium includes converting digital data from the communications medium to analog signals, and outputting the analog signals to the telephony line with a composite MOSFET-bipolar driver stage.